1. Related Technical Fields
Related technical fields include map information generating systems. In particular, related technical fields include systems for generating new road information that is added to map information stored in a navigation device or the like.
2. Related Art
Navigation devices provide guidance for vehicles, enabling a driver to reach a desired destination easily. Such devices are capable of detecting the current position of a vehicle using a GPS receiver, obtaining map data corresponding to the current position from a recording medium, or through a network, and displaying the obtained map data on a display. On the basis of the map data, a map image showing the area around the current position of the vehicle displayed on the display, and a vehicle position mark (location) is superposed on the map image. By scrolling the map image in accordance with movement of the vehicle or moving the vehicle position mark while the map image is fixed on the screen, the current geographical location of the vehicle can be learned at a glance.
New roads are constructed every year. At the same time, existing roads are destroyed and modified. In this case, a problem arises in that information relating to new roads constructed after the map data of the navigation device have been generated is not recorded in the map information data. In other words, the navigation device finds recommended routes that do not pass along the new roads or include destroyed roads. To avoid this problem, the map data stored in the navigation device must be updated at intervals of a certain time period. Such updating is performed by purchasing a new DVD and replacing the old DVD with the new DVD, or overwriting the content of the HDD on the basis of update map data distributed from a map information distribution center.
New road information is typically generated on the basis of survey data obtained when a person actually surveys the new road on site. However, an extremely large number of new roads are built every year, and therefore a huge amount of time is required to survey all of the necessary items in such a manner. As a result, a considerable amount of time is required before new roads are reflected in the map data of the navigation device, leading to a reduction in the reliability of the navigation device. Hence, attempts have been made to generate new road information using a vehicle traveling history. For example, Japanese Patent Application Publication 2004-251790 (e.g., page 8 to page 9, FIG. 4) describes a map information updating system for updating map data by generating new road information automatically on the basis of traveling locus data of a vehicle when it is determined that the vehicle has been traveling continuously along a road that does not exist in the map data of the navigation device.